Agomelatine is the first antidepressant that acts as an agonist of melatonin MT1 and MT2 receptors and an antagonist of 5-HT2C at the same time. Due to these two properties, agomelatine can be used as a novel antidepressant to recover the severely damaged biologic rhythm of melancholic patients. Agomelatine is a melatonergic antidepressant developed by the pharmaceutical company Servier and commercially available under the trade names of Valdoxan, Melitor, Thymanax, etc. It is marketed for the treatment of major depressive disorders and reported to cause neither withdrawal symptoms nor sexual dysfunction in relation to other antidepressants and to have favorable effects on sleep disorders (insomnia). According to the new clinical results announced in the 31th ECNP (European College of Neuropsychopharmacology) congress, agomelatine is far greater in antidepressant efficacy than the existing classes of antidepressants, SSRI (Selective Serotonin Reuptake Inhibitor) and SNRI (Serotonin Noradrenaline Reuptake Inhibitor).
However, agomelatine with such a great efficacy has too low solubility to display its efficacy. For improving the solubility of agomelatine, many studies have been made on the polymorph forms and co-crystals of agomelatine.
A recent patent application discloses an agomelatine co-crystal using an aromatic polyhydric alcohol to enhance the solubility and dissolution rate (KR Patent Application No. 10-2014-0033531). But, there is still a need for a novel preparation method of preparing agomelatine co-crystals that is designed for the higher process efficiency or easy to apply in the commercial mass production than the conventional preparation methods that are associated with removal of organic solvents and grinding.